More results from my 3500Z!

[rsisbetter]

great job dave!

[Superdave]

Some places do have 93 but they're hard to find anymore...

[1988GTU]

91 (premium).

That's premium?! LOL
94 over here is considered premium, but at $3.15+ a gallon it hurts.

[Superdave]

What octane rating are you using? You might be at the point that you can add more fuel without change or actually hurt performance (bog, poor fuel econ) , but if you decrease the fuel while bumping up the octane you might see better results.

91 (premium)


I'd like to put it on the dyno and back off the spark timing to around 28 degrees, then get the WOT fueling in order. then start bumping it up a degree at a time. Once i sell my other "toy" i should have the money to play on the dyno a little bit...

part throttle and cruse fueling is easy to fix, since i built it as a track setup i'm more worried about how it runs in PE mode than anything.

[1988GTU]

I know the AFR's are rich and it's quite possible that the spark timing is too far advanced at 36 degrees. I did get 1 knock count in that run and it did pull a little timing.

What octane rating are you using? You might be at the point that you can add more fuel without change or actually hurt performance (bog, poor fuel econ) , but if you decrease the fuel while bumping up the octane you might see better results.

[sprucegagt]

Humm question...

When your just cruising around, how steady does your wideband stay? Even though my fuel trims stay solid, the wideband reads anywhere from 14-15.5 while just cruising. When I accelerate off a stoplight, the wideband dips to 16 or 17 then straight back to 14-15.5 range.

Also on decel, say I run up to 80 and totally let off the gas, the wideband pegs at max lean till I slow down or till I hit the gas at all.

Is all of this normal?

During normal cruise conditions its common for your O2 to read anywhere between 14.1 - 15. The system is not perfect so it can't hold 14.7 all the time.

On acceleration you should see your wideband dip slightly richer to something in the high 13s. Since your getting 16 and 17 it sounds like your AE table needs some adjustment. Does your car bog or not have good throttle response?

I know for OBDII if you are over 50 MPH and decelerating then the fuel injectors will shut down to save fuel. That's why you see a big lean condition. Don't worry though, it's normal.

[Superdave]

that's pretty much how mine is..

cruse bounces between 14.0 and 16.5, full decel pegs it out to all 9's when i let off at the strip and ride the gears down (my brakes suck). When i acel from a stoplight it actually goes into the 13's then once i reach a crusing speed it levels off.


my wideband is in the header crossover so it's only running off the front 3 cyls, it might not bounce around as band if it was reading all 6. I've thought about moving it to the Y pipe, but the thought of a $50 sensor down there is a little scary.. my car isn't exactly high off the ground.

[PCGUY112887]

Humm question...

When your just cruising around, how steady does your wideband stay? Even though my fuel trims stay solid, the wideband reads anywhere from 14-15.5 while just cruising. When I accelerate off a stoplight, the wideband dips to 16 or 17 then straight back to 14-15.5 range.

Also on decel, say I run up to 80 and totally let off the gas, the wideband pegs at max lean till I slow down or till I hit the gas at all.

Is all of this normal?

[Superdave]

Forgot about this till today...


Here is the breakdown of power VS the AFR measured at the tailpipe.

http://www.3500z.com/3500/Misc/Dynobreakdown.jpg

I know the AFR's are rich and it's quite possible that the spark timing is too far advanced at 36 degrees. I did get 1 knock count in that run and it did pull a little timing...


Here is a datalog from that run: http://www.3500z.com/3500/Misc/dyno2.csv

[Superdave]

I'll dig up the AFR VS RPM breakdown and post it up tonight.. It got drawn on but i think it's still readable.

[SappySE107]

I remember the af part but I guess I completely skipped the part about 0 kr. ok, well I can't think of any other reason for the line to be like that.

[1988GTU]

we ran into some strange stuff..


The engine likes high 11 to low 12.x AFR's.. the leaner we took it the less power it made. Dropping the spark advance from 36 to 34 lost me about 2 HP in the top end as well.

I got 0 knock counts during the session! (and yes the sensor works, LOL)

....

[SappySE107]

Id like to know why the graph is so extreme for high and low spots. I know what tuning does in regards to the jittery lines, but that is borderline absurd. How much KR do you have?

How big are the videos? We have 200 gig free. I gotta hear what that sounds like on a dyno.

[Superdave]

Here is a good pic..



Must have been right after it hit the rev limiter.. the WBo2 was reading a little lean there at fuel cutoff..

[Superdave]

It idles around 1200 RPM cold and 1150 warm.. and still is pretty choppy.


91 octaine and a 350 TPI fuel pump @ 55 PSI


I'll post dyno vids and track vids as soon as Moonwell gets them uploaded to his server.